Sub-block based temporal motion vector predictor with an motion vector offset

Abstract

Aspects of the disclosure provide a method and an apparatus including processing circuitry that determines, based on a syntax element in a coded video bitstream, that a current block including a plurality of subblocks is coded in a subblock-based temporal motion vector prediction (SbTMVP) mode. Motion vector offset (MVO) information indicating an MVO is received. The MVO indicates a motion offset of a displacement vector (DV) used to adjust a location of a collocated block in a collocated reference picture. An updated DV of the current block is determined based on the DV and the MVO. SbTMVP information of a respective subblock in the plurality of subblocks is derived based on motion information of a corresponding subblock in the collocated block indicated by the updated DV. The plurality of subblocks in the SbTMVP mode is reconstructed based on the SbTMVP information of the subblock in the plurality of subblocks.

What is claimed is: 
     
         1 . A method of video decoding in a decoder, comprising:
 receiving a coded video bitstream comprising a current picture, the current picture including a current block, the current block including a plurality of subblocks;   determining, based on a syntax element in the coded video bitstream, that the current block including the plurality of subblocks is coded in a subblock-based temporal motion vector prediction (SbTMVP) mode;   obtaining motion vector offset (MVO) information of the current block that indicates an MVO, the MVO indicating a motion offset of a displacement vector (DV) that is used to adjust a location of a collocated block in a collocated reference picture;   determining an updated DV of the current block based on the DV and the MVO of the current block, the updated DV indicating the adjusted location of the collocated block in the collocated reference picture;   deriving SbTMVP information of a respective subblock in the plurality of subblocks based on at least motion information of a corresponding subblock in the collocated block indicated by the updated DV; and   reconstructing the plurality of subblocks in the SbTMVP mode based on the SbTMVP information of the subblock in the plurality of subblocks.